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Central Nervous System Most highly organized and complex system of the body -Communication and coordination system of the body -Seat of intellect and reasoning -Consists of the brain, spinal cord, and nerves NEURON = Nerve cell Transmits a message from one neuron to the next NEUROGLIA = nerve “glue”, holds nerve together DENDRITES Nerve cell processes that carry impulse to the neuron axon May be one or many AXON Carries impulse away from neuron Only one on a neuron dendrites NEURILEMMA (MYELIN SHEATH) Myelin is a fatty substance that protects the axon Speeds up the nerve impulse as it travels along the axon SYNAPSE – space between neurons, messages go from one cell to the next The ends of the dendrites and axons never touch at the synapse So how is the nerve message continued along the axon/dendrite route??? The synapse contains Neurotransmitters Chemicals which help the message “jump” across the synapse i.e. Dopamine, Epinephrine Acetylcholine Endorphins are neurotransmitters produced in the brain that reduce pain They have also been known to induce euphoria. Drugs such as morphine, heroine and cocaine are classic endorphin-releasing entities Laughter, chocolate, acupuncture, exercise trigger an endorphin release “runner’s high” All neurons have 2 characteristics: 1. irritability: neurons can react when stimulated 2. conductivity: neurons can transmit an impulse to another neuron 3 Types of Neurons SENSORY NEURONS (AFFERENT) – emerge from the skin or sense organs, carry impulses to spinal cord and brain MOTOR NEURONS (EFFERENT) – carry messages from brain and spinal cord to muscles and glands INTERNEURONS (ASSOCIATIVE NEURONS)– carry impulses “in between” sensory neurons and motor neurons found in the spinal cord The Brain 3 lb mass of soft nervous tissue 100 billion neurons Protected by: -Cranium (craino is root word for skull) -3 membranes called meninges, and -cerebrospinal fluid (CSF) brain tissue will die in 4-8 mins. without O2 Coverings of the Brain (MENINGES) DURA MATER – outer brain covering, lines the inside of the skull, tough connective tissue. ARACHNOID – middle layer, resembles fine cobweb PIA MATER – covers the brain’s surface, CEREBROSPINAL FLUID – bathes the brain and spinal cord, liquid shock absorber SUBDURAL SPACE – between dura and arachnoid, contains CSF SUBARACHNOID SPACE - between arachnoid and pia mater, filled with CSF What would a subdural hematoma be??? Bruise on the brain under the dura mater Subdural Hematoma Ventricles of the Brain Brain contains four cavities filled with cerebrospinal fluid. Right and left lateral ventricles largest Third ventricle below R and L ventricles Fourth ventricle is below the 3rd, extends into spinal cord CHOROID PLEXUS – network of blood vessels lining the ventricles forms cerebrospinal fluid BLOOD-BRAIN BARRIER – choroid plexus capillaries prevent substances (like antibiotics) from penetrating brain tissue – this makes infections difficult to cure i.e. meningitis HOWEVER it prevents harmful substances from entering the brain tissue Meningitis inflammation of the meninges causes excess production of CSF What type of S/S might you see??? Headache Stiff neck What do we do to relieve some of the extra CSF??? LUMBAR PUNCTURE LUMBAR PUNCTURE (spinal tap)– removal of CSF from spinal canal needle puncture between 3rd and 4th lumbar vertebrae Why would we place the needle at this vertebrae?? Spinal Cord ends at L2 Used to diagnose Tumors, meningitis, other infections PARTS OF THE BRAIN CEREBRUM CEREBELLUM DIENCEPHALON BRAIN STEM CEREBRUM Largest part of the brain Divided into R and L hemispheres We know that our brain is divided into 2 hemispheres The L side of the brain controls the R side of the body and vice versa If we have a L sided CVA, which side of the body will be effected??? The R side Fissures deep grooves in the brain They are important because they specify “functional area” Corpus Callosum largest fissure, wide band of fibers that hold the R and L hemispheres together SULCI – shallow grooves separating cerebral convolutions CONVOLUTIONS – elevated ridges that pop up on the surface of the cerebrum they increase the surface area of the brain which increase our “gray matter” The more gray matter you have the SMARTER YOU ARE!!!! Cerebrum parietal Parietal frontal Temporal temporal occipital Occipital Functions of the Cerebrum Determined by the 4 lobes All lobes are covered by the cerebral cortex or gray matter 1. Frontal Lobe - voluntary motor functions -speech -emotions/personality -memory/reasoning/will power -learning/intellect The L frontal lobe holds the center that allows us to speak If we have a CVA in that area we may know WHAT we want to say, but be unable to say it 2. Parietal Lobe receives and interprets -pain -touch -heat/cold 3. Occipital Lobe controls eyesight 4. Temporal Lobe controls impulses for -auditory -smell At the junction of the temporal, parietal and occipital lobes is the area that allows us to RECOGNIZE and INTERPRET written and spoken words CEREBRAL DOMINANCE 90-95% of the population is L side dominant meaning we are R handed But intellectually, why do we use one side of our brain more than others…. or do we???? How does memory work???? P.140 Brain teaser CEREBELLUM 2ND largest part of the brain Looks like the “onion” part at the back of the brain Controls all body functions related to skeletal muscles Cerebellum 1. Balance: works with the inner ear, sends messages to cerebral cortex to restore and maintain balance 2. Muscle tone all muscles have tone 3. Coordination of muscle movements makes muscle movements smooth, flowing and coordinated Coordinates complex skills such as walking, talking, etc. i.e. Cerebellum coordinates 50 muscles and 30 bones of the hand and arm to raise your hand and prevent a blow to your face DIENCEPHALON Located in the very middle of the brain Composed of: THALAMUS and HYPOTHALAMUS and 1 gland PITUITARY GLAND 1. Thalamus relay station for impulses going to the cerebral cortex 2. Hypothalamus “brain of the brain” connected to the pituitary gland and tells it when to release hormones Hypothalamus has multiple functions: - controls autonomic nervous system (BP and P) -maintains body temperature -appetite control -water balance -sleep control -intestinal peristalsis/secretions -makes oxytocin (causes labor) synthetic form is Pitocin “Pit drip” It also is associated with emotional control as a part of the limbic system PAGE 148 BRAIN STEM contains 3 parts: Midbrain Pons Medulla oblongata Pons and midbrain serve as relay pathways for impulses between cerebrum, cerebellum, spine and body Brain stem contains the Reticular formation system -involves the sleep/wake cycle and if it is damaged, coma results Medulla Oblongata IT IS THE NUCLEI OF ALL VITAL FUNCTIONS!!!! -PULSE -BP -Rate/depth of respirations -Swallowing and vomiting SPINAL CORD Continues down from the brain to the 2nd lumbar vertebrae Lies within the spinal column, surrounded by the meninges and CSF Functions: Reflex center Pathway for nerve impulses to and from the brain DIVISIONS OF THE NERVOUS SYSTEM 1. Central Nervous System brain and spinal column 2. Peripheral Nervous System “to the side” Contains the: a. Autonomic Nervous System (ANS) b. Cranial nerves c. Spinal Nerves AUTONOMIC NERVOUS SYSTEM “involuntary” “automatic” Controls activities of visceral organs 1. SYMPATHETIC NERVOUS SYSTEM “fight or flight” system – when the body perceives danger, SNS sends message to adrenal gland to secrete adrenaline aka: epinephrine So what does Adrenaline do to us??? What does it feel like when you get “butterflies” Increase pulse and BP Decrease blood flow to stomach/intestines Dry mouth Nausea Sweaty 2. PARASYMPATHETIC NERVOUS SYSTEM – counters effects of SNS, The SNS and PNS work as a pair to balance each other What do we call a constant state of “fight or flight”??? STRESS!!!!!!! To much stress hormone (adrenaline) can cause health problems! -heart disease, -increased BP, -headaches -digestive problems SPINAL NERVES Originate at spinal cord and go through openings in vertebrae 31 pairs of spinal nerves Nerves divide, form a network or “plexus” and serve a body segment 1.CERVICAL PLEXUS serves the neck and shoulder Phrenic nerve stimulates diaphragm 2. BRACHIAL PLEXUS serves hands/wrists RADIAL nerve Lower 2 sections are sometimes refered to as the “horse's tail” 3. LUMBAR PLEXUS stimulates the anterior hip and thigh, buttocks FEMORAL NERVE 4. SACRAL PLEXUS stimulates posterior leg/thigh SCIATIC NERVE largest nerve in the body Reflex Act simplest type of nerve response i.e. blinking your eye Every reflex is proceed by a stimulus Receptors pick up the stimulus Response to the stimulus is called a reaction Most familiar reflex is the knee-jerk reflex Tap the patella tendon with a percussion hammer and the knee jerks Traumatic Brain Injury Concussion: brain is only slightly injured Contusion result of severe head injury/trauma i.e. a contusion to the brain stem would result in a coma What structure has been damaged?? Reticular formation system -Contracoup injury: brain slams against cranium in one direction and then back in the other direction After head trauma/injury, pressures increases in the cranium due to: 1. cerebral edema swelling in and around the brain 2. intracranial hemorrhage bleeding in the cranium If pressure is not relieved, pressure crushes the diencephalon and brain stem Head trauma can result in: 1. stupor brief periods of consciousness 2. coma no consciousness 3. vegetative state various sleep wake cycles but no response to stimulus 4. persistent vegetative state (PVS) a permanent state of no responsiveness Glasgow Coma Scale A scale based on the patient’s ability to respond to commands i.e. open your eyes, respond verbally, move their limbs Ranges from a score 3-15 The lower the score, the more severe the head injury Examples of brain trauma/injury: subdural hematoma: bruise between the dura mater and arachnoid layers Subarachnoid hematoma bruise between the arachnoid layer and pia mater CVA Aneurysms (causes intracranial bleeding) Blunt trauma MENINGITIS Inflammation of the meninges of the brain and spinal cord Symptoms – headache, fever and stiff neck How would this be diagnosed??? LP May be bacterial or viral If bacterial, may be treated with antibiotics ENCEPHALITIS (encephal is root word for inside the brain) Inflammation of the brain EPILEPSY Seizure disorder, characterized by recurring and excessive discharge from neurons “pinball” Cause – uncertain, multiple Grand mal – severe, convulsive seizure Petit mal – milder, may appear to be daydreaming Treatment anticonvulsants Care for a Person who is seizing Get them on the floor DO NOT TRY TO PUT ANYTHING IN THE THEIR MOUTHS!!! Gently cradle their heads and turn it to the side DO NOT TRY TO HOLD THEM DOWN After seizure is over, allow them to rest CEREBRAL PALSY Disturbance in voluntary muscular action due to brain damage, birth trauma, abnormal brain development Symps – head rolling, grimacing, difficult speech and swallowing, spastic paralysis in limbs No impairment of intellect POLIOMYELITIS (viral) Disease of nerve pathways of spinal cord – causing paralysis Almost eliminated in USA (vaccine) HYDROCEPHALUS Increase of cerebrospinal fluid within ventricles Causes enlargement of head, usually noticed at birth Can be caused by trauma Bypass or shunt performed to relieve pressure PARKINSON’S DISEASE Symps – tremors, shuffling gait, pill-rolling, and muscular rigidity Decrease in neurotransmitters probably dopamine Rx –drugs to treat symptoms MULTIPLE SCLEROSIS (MS) Immune cells attack myelin sheath of axon What does the myelin sheath do??? Transmission of nerve impulses blocked or lost Cause – unknown Symps – weakness of extremities, loss of coordination, double vision, mostly women, age 20 – 40, Rx –drugs to slow progression DEMENTIA Loss of 2 areas of complex behavior i.e. language, memory, visual abilities, or judgment ALZHEIMER’S DISEASE Progressive disease that begins with problems remembering Cerebral cortex degenerates, neurons become tangled Cause – unknown First stage (2-4 years) confusion, short-term memory loss, poor judgment 2nd stage (2-10 years) difficulty recognizing people, motor problems, and loss of social skills 3rd stage (1-3 years) inability to recognize oneself, weight loss and aphasia( inability to speak) NEURALGIA pain along a nerve NEURITIS: inflammation of a nerve PARESTHESIA tingling, burning, and crawling of skin 1. Sciatica neuritis of the sciatic nerve pain radiates down the back of the leg 2. Trigeminal Neuralgia neuritis of the Trigeminal nerve, 3. Bell’s Palsy involves the facial nerve, eyes may not close properly, mouth may droop 4. SHINGLES herpes zoster Same virus as chicken pox, it goes dormant and lies on the spinal nerves Reappears along the back Causes severe itching and pain Generally seen in older adults Cerebral Vascular Accident “Stroke” CVA Interruption of blood and O2 to brain causing tissue death Risk Factors: same as for MI Causes of CVA -90% caused by blood clots lodged in carotid arteries -ruptured blood vessels in the brain “brain bleed” Symptoms Hemiplegia paralysis on one side of the body, opposite side of the body Sudden, severe headache, dizziness Sudden loss of vision in one eye Aphasia, Dysphasia (swallowing) Coma, possible death Treatment Get to the hospital immediately!! If a clot, treatment aimed at dissolving clot What would we use??? Prevention is the best treatment one aspirin a day TIA’s “mini strokes” transient ischemic attacks PARALYSIS – loss of power of motion or sensation PARAPLEGIA – paralysis in lower extremities, seen in spinal cord injuries QUADRIPLEGIA – paralysis all four extremities, also seen in spinal cord injuries Diagnostic Tests ELECTROENCEPHALOGRAM (EEG) - recording of the electrical activity of the brain CAT SCAN – (Computerized Axial Tomography) Combines X-ray emission with nuclear medicine MRI – Magnetic Resonance Imaging – uses a magnetic field along with radio frequency to produce cross-section images of the body. Patient inserted into chamber built within a huge magnet Eyes in relation to the brain